1. Technical Field
The disclosure relates to an accelerometer which is manufactured by Micro Electro Mechanical System (MEMS) technology and has the capability of sensing two axes or three axes acceleration.
2. Description of Related Art
Many non-military applications require accelerometer with the ability to sense acceleration along three mutually orthogonal axes. Especially for the applications in modern consumer electronic devices, the size and cost of a multi-axis accelerometer is demanded. The art for a compact accelerometer with a single sensing structure for sensing acceleration along three mutually orthogonal axes is thus needed.
U.S. Pat. No. 6,201,284 discloses an accelerometer which utilizes one single sensing structure with proof masses to detect the acceleration of X, Y and Z axes. The proof masses detecting X-axis and Y-axis accelerations may be interfered by the motion of Z-axis proof mass. The design likes this will cause cross-axis sensitivities poor. U.S. Pat. No. 6,845,670 discloses a three-axis accelerometer with only one proof mass, however, this accelerometer adopts a set of non de-coupled springs for detecting the acceleration of three axes. This may affect the performance of cross-axis sensitivity seriously. In addition, the motion of the proof mass for sensing Z-axis acceleration disclosed by U.S. Pat. No. 6,845,670 may be a combination of rotation and movement, and this may results in poor linearity of the accelerometer.
U.S. Pat. No. 7,258,012 which disclosed another accelerometer design with one sensing structure, but the motion of its Z-axis proof mass also may lead the Z-axis output with poor linearity.